We present the expected observational properties of a general relativistic instability supernova (GRSN) from the 55,500 Msun primordial (Population III) star. Supermassive stars exceeding 1e4 Msun may exist in the early Universe. They are generally considered to collapse through the general relativistic instability to be seed black holes to form supermassive (~ 1e9 Msun) black holes observed as high-redshift quasars. Some of them, however, may explode as GRSNe if the explosive helium burning unbinds the supermassive stars following the collapse triggered by the general relativistic instability. We perform the radiation hydrodynamics simulation of the GRSN starting shortly before the shock breakout. We find that the GRSN is characterized by a long-lasting (550 d) luminous (1.5e44 erg/s) plateau phase with the photospheric temperature of around 5000 K in the rest frame. The plateau phase lasts for decades when it appears at high redshifts and it will likely be observed as a persistent source in the future deep near-infrared imaging surveys. Especially, the near-infrared images reaching 29 AB magnitude that can be obtained by Galaxy and Reionization EXplorer (G-REX) and James Webb Space Telescope (JWST) allow us to identify GRSNe up to z ~ 15. Deeper images enable us to discover GRSNe at even higher redshifts. Having extremely red color, they can be distinguished from other persistent sources such as high-redshift galaxies by using color information. We conclude that the deep near-infrared images are able to constrain the existence of GRSNe from the primordial supermassive stars in the Universe even without the time domain information.
The origin of high-redshift quasars and their supermassive black hole engines is unclear. One promising solution is the collapse of a primordial supermassive star. Observational confirmation of this scenario may be challenging, but a general relativistic instability supernova provides one avenue for such. Previous studies have found that a general relativistic instability supernova has a potentially decades-long plateau phase visible to JWST at high redshift. In this work, we examine stars with mass just below the general relativistic instability supernova mass range. These stars pulsate, ejec…
Observed supermassive black holes in the early universe have several proposed formation channels, in part because most of these channels are difficult to probe. One of the more promising channels, the direct collapse of a supermassive star, has several possible probes including the explosion of a helium-core supermassive star triggered by a general relativistic instability. We develop a straightforward method for evaluating the general relativistic radial instability without simplifying assumptions and apply it to population III supermassive stars taken from a post Newtonian stellar evolution …
Supermassive stars forming at $z \sim$ 15 - 20 are one of the leading contenders for the origin of the first quasars, over 200 of which have now been discovered at $z >$ 6. These stars likely form in pristine, atomically cooled haloes immersed in strong Lyman-Werner UV backgrounds or in highly supersonic baryon streaming flows. Atomic cooling triggers catastrophic baryon collapse capable of building up stars at rates of up to $\sim$1 M$_{\odot}$ yr$^{-1}$. Here we examine the evolution of supermassive stars with a much larger and finer grid of accretion rates than in previous studies with the …
Primordial supermassive stars (SMSs) formed in atomic-cooling halos at z ~ 15 - 20 are leading candidates for the seeds of the first quasars. Past numerical studies of the evolution of SMSs have typically assumed constant accretion rates rather than the highly variable flows in which they form. We model the evolution of SMSs in the cosmological flows that create them using the Kepler stellar evolution and implicit hydrodynamics code. We find that they reach masses of 1 - 2 x $10^5 M_{\odot}$ before undergoing direct-collapse to black holes (DCBHs) during or at the end of their main-sequence hy…
Supermassive primordial stars are suspected to be the progenitors of the most massive quasars at z~6. Previous studies of such stars were either unable to resolve hydrodynamical timescales or considered stars in isolation, not in the extreme accretion flows in which they actually form. Therefore, they could not self-consistently predict their final masses at collapse, or those of the resulting supermassive black hole seeds, but rather invoked comparison to simple polytropic models. Here, we systematically examine the birth, evolution and collapse of accreting non-rotating supermassive stars un…
We argue that the stable (color singlet) supermassive gravitinos proposed in our previous work can serve as seeds for giant primordial black holes. These seeds are hypothesized to start out as tightly bound states of fractionally charged gravitinos in the radiation dominated era, whose formation is supported by the universally attractive combination of gravitational and electric forces between the gravitinos and anti-gravitinos (reflecting their `almost BPS-like' nature). When lumps of such bound states coalesce and undergo gravitational collapse, the resulting mini-black holes can escape Hawk…
The first generation of stars is quite unique. The absence of metals likely affects their formation, with current models suggesting a much more top-heavy initial mass fraction than what we observe today, and some of their other properties, such as rotation rates and binarity, are largely unknown or constrained by direct observations. But even non-rotation single stars of a given mass will evolve quite differently due to the absence of the metals: the stars will mostly remain much more compact until their death, with the hydrogen-rich later reaching down ten teems deeper in radius then in moder…
Building on the insight that primordial black holes can arise from the formation and subsequent gravitational collapse of bound states of stable supermassive elementary particles during the early radiation era, we offer a comprehensive picture describing the evolution and growth of the resulting mini-black holes through both the radiation and matter dominated phases, until the onset of (small scale) inhomogeneities. This is achieved by means of an exact metric solving Einstein's equations throughout both phases. We show that, thanks to a special enhancement effect producing an effective horizo…
Supernova microlensing as a probe of ultracompact minihalos and primordial cosmology
Institute for Particle Physics Phenomenology, Department of Physics, Durham University（达勒姆大学粒子物理现象学研究所）；Center for Particle Cosmology, Department of Physics and Astronomy, University of Pennsylvania（宾夕法尼亚大学天体物理学与宇宙学中心）；Max Planck Institute for Gravitational Physics (Albert Einstein Institute)（马克斯·普朗克引力物理研究所（阿尔伯特·爱因斯坦研究所））；Instituto de Física Teórica UAM/CSIC（马德里自治大学/西班牙国家研究委员会理论物理研究所）
该研究提出利用超新星微引力透镜搜寻超致密小暗晕等延展暗结构，计算其探测效率并可约束原初功率谱，有望借助Vera C. Rubin天文台的LSST超新星样本成为早期宇宙物理的互补探针。
NANOGrav 15-year gravitational-wave signals from binary supermassive black-holes seeded by primordial black holes, and implications for the origins of Little Red Dots
Graduate University for Advanced Studies (SOKENDAI)（高等研究院）；High Energy Accelerator Research Organization (KEK)（高能加速器研究机构）；National Astronomical Observatory of Japan（日本国立天文台）；University of Tokyo（东京大学）；The University of Tokyo（东京大学）
Nuclear star clusters that surround supermassive black holes (SMBHs) in galactic nuclei are among the densest systems in the Universe, harbouring millions of stars and compact objects (COs). Within a few parsecs from the SMBH, stars can form binaries. In this paper, we model the supernova (SN) process of massive binaries that are born in proximity of the SMBH and that produce CO binaries. These binaries can later merge via emission of gravitational waves as a consequence of the Lidov-Kozai mechanism. We study the dynamical evolution of these systems by means of high-precision $N$-body simulati…
Memoirs of the curvaton: non-perturbative non-Gaussianity and supermassive primordial black holes
Keemilise ja Bioloogilise Füüsika Instituut（化学与生物物理研究所）；Tallinn University of Technology（塔林科技大学）；Center for Astrophysics and Space Science (CASS), New York University Abu Dhabi（纽约大学阿布扎比分校天体物理学与空间科学中心）
研究曲率子超出二次势的自相互作用，通过简化作用量构建非高斯映射，发现自相互作用可增强或抑制非高斯性，并利用强正非高斯性在COBE/FIRAS约束下产生超大质量原初黑洞种子，解释JWST观测的Little Red Dots。
Appreciable star formation, and, therefore, numerous massive stars, are frequently found near supermassive black holes (SMBHs). As a result, core-collapse supernovae in these regions should also be expected. In this paper, we consider the observational consequences of predicting the fate of supernova remnants (SNRs) in the sphere of influence of quiescent SMBHs. We present these results in the context of `autarkic' nuclei, a model that describes quiescent nuclei as steady-state and self-sufficient environments where the SMBH accretes stellar winds with no appreciable inflow of material from be…
Supermassive stars have been proposed as the progenitors of the massive ($\sim 10^{9}\,\rm{M}_{\odot}$) quasars observed at $z\sim7$. Prospects for directly detecting supermassive stars with next-generation facilities depend critically on their intrinsic lifetimes, as well as their formation rates. We use the 1D stellar evolution code Kepler to explore the theoretical limiting case of zero-metallicity, non-rotating stars, formed monolithically with initial masses between $10\,\rm{kM}_{\odot}$ and $190\,\rm{kM}_{\odot}$. We find that stars born with masses between $\sim60\,\rm{kM}_{\odot}$ and …
Supermassive primordial stars with masses exceeding $\sim10^5\,M_{\odot}$ that form in atomically cooled halos are the leading candidates for the origin of high-redshift quasars with $z>6$. Recent numerical simulations, however, find that multiple accretion disks can form within a halo, each of which can host a supermassive star. Tidal interactions between the disks can gravitationally torque gas onto their respective stars and alter their evolution. Later, when two satellite disks collide, the two stars can come into close proximity. This may induce additional mass exchange between them. We i…
Primordial Black Hole Triggered Type Ia Supernovae II: Comparison with Supernova Remnants and Galactic Chemical Evolution
SUNY Polytechnic Institute（纽约州立大学波利技术学院）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo（东京大学基础物理学与数学宇宙研究所（WPI））；University of California, Los Angeles（加州大学洛杉矶分校）；Chubu University（中部大学）
Supermassive black holes observed at high redshift $z\gtrsim6$ could grow from direct collapse black holes (DCBHs) with mass $\sim10^5\,M_{\odot}$, which result from the collapse of supermassive stars (SMSs). If a relativistic jet is launched from a DCBH, it can break out of the collapsing SMS and produce a gamma-ray burst (GRB). Although most of the GRB jets are off-axis from our line of sight, we show that the energy injected from the jet into a cocoon is huge $\sim10^{55-56}\,{\rm{erg}}$, so that the cocoon fireball is observed as ultra-luminous supernovae of $\sim10^{45-46}\rm{\,erg\,s^{-1…
Pair-instability supernovae (PISNe) are the ultimate cosmic lighthouses, capable of being observed at z<25 and revealing the properties of primordial stars at cosmic dawn. But it is now understood that the spectra and light curves of these events evolved with redshift as the universe became polluted with heavy elements because chemically enriched stars in this mass range typically lose most of their hydrogen envelopes and explode as bare helium cores. The light curves of such transients can be considerably dimmer in the near infrared (NIR) today than those of primordial PISNe of equal energy a…
Collapsing supermassive stars ($M \gtrsim 3 \times 10^4 M_{\odot}$) at high redshifts can naturally provide seeds and explain the origin of the supermassive black holes observed in the centers of nearly all galaxies. During the collapse of supermassive stars, a burst of non-thermal neutrinos is generated with a luminosity that could greatly exceed that of a conventional core collapse supernova explosion. In this work, we investigate the extent to which the neutrinos produced in these explosions can be observed via coherent elastic neutrino-nucleus scattering (CE$ν$NS). Large scale direct dark …
The black hole binary properties inferred from the LIGO gravitational wave signal GW150914 posed several serious problems. The high masses and low effective spin of black hole binary can be explained if they are primordial (PBH) rather than the products of the stellar binary evolution. Such PBH properties are postulated ad hoc but not derived from fundamental theory. We show that the necessary features of PBHs naturally follow from the slightly modified Affleck-Dine (AD) mechanism of baryogenesis. The log-normal distribution of PBHs, predicted within the AD paradigm, is adjusted to provide an …
